In the field of printing, the most common type printer has been the printer which impacts against record media that is caused to be moved past a printing line or line of printing. As is well-known, the impact printing operation depends upon the movement of impact members, such as print hammers or wires or the like, which are typically moved by means of an electromechanical drive system and which system enables precise control of the impact members.
In the field of dot matrix printers, it has been quite common to provide a print head which has included therein a plurality of print wire actuators or solenoids arranged or grouped in a manner to drive the respective print wires a very short, precise distance from a rest or non-printing position to an impact or printing position. The print wires are generally either secured to or engaged by the solenoid plunger or armature which is caused to be moved such precise distance when the solenoid coil is energized and wherein the plunger or armature normally operates against the acton of a return spring.
It has also been quite common to provide an arrangement or grouping of such solenoids in a circular configuration to take advantage of reduced space available in the manner of locating the print wires in that specific area between the solenoids and the front tip of the print head adjacent the record media. In this respect, the actuating ends of the print wires are positioned in accordance with the circular arrangement and the operating or working ends of the print wires are closely spaced in vertically-aligned manner adjacent the record media. The availability of narrow or compact actuators permits a narrower or smaller print head to be used and thereby reduces the width of the printer because of the reduced clearance at the ends of the print line. The print head can also be made shorter because the narrow actuators can be placed in side-by-side manner closer to the record media for a given amount of wire curvature.
In the wire matrix printer which is utilized for receipt and journal printing operation, the print head structure may be a multiple element type and may be horizontally disposed with the wire elements aligned in a vertical line and supported on a print head carriage which is caused to be moved or driven in a horizontal direction for printing in line manner across the receipt or journal paper and wherein the drive elements or transducers may be positioned in a circular configuration with the respective wires leading to the front tip of the print head. In the wire matrix printer which is utilized for business forms or like record media printing operation, the print head may be oriented in a manner wherein the nose is pointed downward for printing on the form, slip or like media while the carriage and print head are moved above and across the form or media in the horizontal direction.
In the dot matrix printer which includes a print head of the circular configuration and multiple element type, there is a requirement for driving an inking ribbon past the print head at one or both ends of travel of the print head during printing operations.
Representative documentation in the field of ribbon drive mechanisms includes U.S. Pat. No. 3,948,382, issued to D. D. Nesbitt et al. on Apr. 6, 1976, which discloses a motor-driven ribbon drive mechanism having a pivotable bar carrying a gear combination mounted so that one gear may mesh with either of two ribbon drive gears depending upon the direction of rotation of the motor.
U.S. Pat. No. 3,990,564, issued to L. L. Crump et al. on Nov. 9, 1976, discloses a ribbon drive mechanism wherein a pair of compensating wheels with overriding clutches are alternately activated to drive the ribbon in one direction regardless of the direction of travel of the print head carriage.
U.S. Pat. No. 4,416,560, issued to D. E. Wood et al. on Nov. 22, 1983, discloses a computer printer carriage control apparatus and a ribbon cassette containing an inked ribbon and ribbon feed mechanism.
U.S. Pat. No. 4,452,542, issued to H. Akazawa on June 5, 1984, discloses an endless timing belt driving a roller operably coupled with a plurality of gears for driving the ribbon in one direction.
U.S. Pat. No. 4,531,849, issued to K. Dobashi on July 30, 1985, discloses a ribbon feed mechanism having a first and a second drive gear, an output gear and an output shaft, and an idler gear held in mesh with the output gear at all times.
U.S. Pat. No. 4,596,480, issued to H. Takada on June 24, 1986, discloses a ribbon feed mechanism wherein a ribbon drive gear for feeding the ribbon is alternately meshed with two drive gears during reciprocation of the carriage to be thereby rotated in a predetermined single direction.
U.S. Pat. No. 4,712,931, issued to K. Ohshima on Dec. 15, 1987, discloses a ribbon drive mechanism that includes an endless timing belt driving a pulley connected with a gear that is swingable to engage one or another gear depending on the rotational direction of the pulley.
And, Japanese Application No. 58-191182, dated Nov. 8, 1983, discloses a drive mechanism wherein an internal gear is swung in an arc to engage with another gear arrangement for driving the ribbon in one direction.